These images, taken with the LEISA infrared camera on the New Horizons
Ralph instrument, show fine details in Jupiter's turbulent atmosphere
using light that can only be seen using infrared sensors. These are "false
color" pictures made by assigning infrared wavelengths to the colors red,
green and blue. LEISA (Linear Etalon Imaging Spectral Array) takes images
across 250 IR wavelengths in the range from 1.25 to 2.5 microns, allowing
scientists to obtain an infrared spectrum at every location on Jupiter. A
micron is one millionth of a meter.
These pictures were taken at 05:58 UT on February 27, 2007, from a
distance of 2.9 million kilometers (1.6 million miles). They are centered
at 8 degrees south, 32 degrees east in Jupiter "System III" coordinates.
The large oval-shaped feature is the well-known Great Red Spot. The
resolution of each pixel in these images is about 175 kilometers (110
miles); Jupiter's diameter is approximately 145,000 kilometers (97,000
miles).
The image on the left is an altitude map made by assigning the color red
to 1.60 microns, green to 1.89 microns and blue to 2.04 microns. Because
Jupiter's atmosphere absorbs light strongly at 2.04 microns, only clouds
at very high altitude will reflect light at this wavelength. Light at 1.89
microns can go deeper in the atmosphere and light at 1.6 microns can go
deeper still. In this map, bluish colors indicate high clouds and reddish
colors indicate lower clouds. This picture shows, for example, that the
Great Red Spot extends far up into the atmosphere.
In the image at right, red equals 1.28 microns, green equals 1.30 microns
and blue equals 1.36 microns, a range of wavelengths that similarly probes
different altitudes in the atmosphere. This choice of wavelengths
highlights Jupiter's high-altitude south polar hood of haze. The edge of
Jupiter's disk at the bottom of the panel appears slightly non-circular
because the left-hand portion is the true edge of the disk, while the
right portion is defined by the day/night boundary (known as the
terminator).
These two images illustrate only a small fraction of the information
contained in a single LEISA scan, highlighting just one aspect of the
power of infrared spectra for atmospheric studies.
